Function acos

external/.d3.js:17486–17488

(x)

const tau = 2 * pi;

function acos(x) {
  return x > 1 ? 0 : x < -1 ? pi : Math.acos(x);
}

function asin(x) {
  return x >= 1 ? halfPi : x <= -1 ? -halfPi : Math.asin(x);